AccessLimiter is a plugin used to restrict access to part of a post in Blog gadget for a user or group of users.

But if you want to prohibit access to other gadgets then you can use ACLs. For this purpose open Registry/Edit ACL keys. All gadgets have a key named 'default' that controls the default permission for that gadget on front end. The default value is true. So if you change it for a gadget to false then no user can access that gadget on front end except Super Administrators or users which have granted access for that gadget (can be set on Users/ACLs).